Dental handpieces are known, which mix air and powder for polishing or cleaning tooth surface, and inject the mixture together with water onto the tooth surface. Dental handpieces of this type are known, for example, from Patent Publication 1, wherein the dental handpiece is composed of a handpiece body and a nozzle. The handpiece body has a container for accommodating powder, an air supply line for supplying air into the container, a mixture transfer line for transferring a mixture of the powder and air to a nozzle, a water supply line for transferring water to the nozzle, and a head (nozzle connector portion) on which the nozzle is attached. The nozzle has a line and an injection port for each of the mixture and the water for separate injection thereof. The nozzle is inserted onto and fit on the head at the tip of the handpiece body, so that the line and the injection port for each of the mixture and the water through the nozzle are brought into communication with the corresponding mixture transfer line and water supply line in the handpiece body. In this way, the mixture of air and powder supplied through the handpiece body is adapted to be injected together with water through the nozzle.
As a nozzle for injecting a mixture of air and powder together with water, there is known a nozzle for use in subgingival treatment, such as disclosed in Patent Publication 2. As disclosed in this publication, a nozzle for subgingival treatment has a connector portion connected to a handpiece body, and a nozzle body extending from the connector portion toward the end, gradually tapering into a thin and flat form. Through the nozzle body, a channel for transferring a mixture of air and powder and a channel for transferring water are separately provided, extending from the connector portion toward the end of the nozzle body, and a mixture injection port and a water injection port for separately injecting the mixture and water are respectively opened in the end of the nozzle body. Examples of a commercial product that are in practical use for general dental or medical institutions include a nozzle entirely made of a resin and 1.62 mm wide and 0.78 mm thick in its end, or a nozzle entirely made of metal and 1.95 mm wide and 0.91 mm thick in its end.
These nozzles are connected to the nozzle connector port of the handpiece body by means of various securing means, such as of an insertion or screwing type, so as to transfer water and the mixture of air and powder supplied through the handpiece body through the lines in the nozzle respectively assigned to the water and the mixture, for injection through the respective injection ports during subgingival treatment, as discussed above.
Patent Publication 1: JP-H10-286268-A
Patent Publication 2: JP-2008-149138-A